As people pay more attention to virtual reality (VR) products, many companies and organizations focus on the development of VR technologies. The VR audio is a key technology in the VR field. The VR audio can provide a user with auditory contents having a spatial resolution, so that the user can have immersive VR application experience. The sense of immersion can be realized only if both the visual sense and the auditory sense are consistent with the real world, as shown in FIG. 1.
FIG. 1 is a schematic diagram of experience of a virtual reality (VR) audio according to the related art.
The VR content source is an issue concerned by many users at present. To enable a user to experience rich VR applications and VR contents, an online virtual content platform becomes a future development trend, and a user can use a VR equipment to browse VR contents on the online virtual content platform in real time. However, the bandwidth use in the browsing process is an issue to be considered.
As one key technology in the existing VR audio, the ambisonics technology records and restores a physical sound field by sound field harmonic decomposition and successive approximation. Ambisonics uses spatial harmonics as independent signals. For L-order spatial ambisonics, (L+1)2 independent spatial harmonic signals are required, an array consisting of (L+1)2 microphones is at least required for pickup, and at least (L+1)2 loudspeakers are required for playback. If the order of an ambisonics signal is higher, the approximation effect of the spatial sound field is better. Therefore, a higher-order ambisonics signal has a better spatial resolution. However, the bandwidth occupancy sharply increases with the increase of the order.
FIG. 2 is a schematic diagram of the spatial resolution of ambisonics sound fields of different orders according to the related art.
FIG. 3A is a schematic diagram of a 3-order ambisonics sound field, where 16 independent signals are required, according to the related art.
To solve the problem in the ambisonics technology that the bandwidth occupancy sharply increases with the increase of the order, a mixed order ambisonics (MOA) technology has been proposed. In the MOA technology, different orders are used for sound fields in a horizontal direction and a vertical direction. When a user gazes at a horizontal plane, the ears are differently sensitive to the sound in the horizontal direction and the sound in the vertical direction, and are more sensitive to the sound in the horizontal direction. Therefore, contents in the horizontal direction are transmitted at a higher order so that the contents in the horizontal direction have a high spatial resolution, meanwhile, contents in the vertical direction are transmitted at a low order, thereby reducing the bandwidth occupancy.
FIG. 3B is a schematic diagram of an MOA sound field according to the related art.
Referring to FIG. 3B, the horizontal direction is at a 3-order (a 3-order two-dimensional ambisonic signal is used in the horizontal direction), the vertical direction is at a 1-order (a 1-order three-dimensional ambisonic signal is used in the vertical direction). When the MOA technology is used, only 8 independent signals are required, and the bandwidth occupancy is equivalent to ½ of that for the ambisonics technology.
However, the existing MOA technology is still not high enough in the spatial resolution accuracy but too high in the bandwidth occupancy.
The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure.